Simulated granite

ABSTRACT

The invention is a ceramic synthetic stone product that is comprised of a brick material. The product is formed by precisely grinding out distortions of an over-sized precursor product, and grinding off at least one side of the die skin of the over-sized precursor product, therein exposing an interior surface that looks like granite. The interior surface is substantially off-white or gray with black crystalline specks. The product is a brick, a tile, an architectural stone, a curvilinear block, a trapezoidal block, or a decorative plate. The major constituents of the brick material are clay, oxide pigments, and a binder. Recycled granite can also be added as well as shale, kaolin and feldspar. The method of making the product is also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to synthetic stone, and more particularly to a ceramic synthetic stone that is a brick material that is comparable in appearance to grades of granite.

2. Prior Art

The patent prior art describing “Artificial Stone” using vitrified or refractory materials dates back to Marc Laffont in U.S. Pat. No. 501,794, where he disclosed fusible clay that is suitable for purposes of building and paving. This was followed shortly thereafter by William and Albert Roach in U.S. Pat. No. 720,739 where they teach an artificial stone comprised of clay, sand, lime, and fluorspar that is fused between 1538 to 1982° C., and then annealed at 204° C. August Deidesheimer, in U.S. Pat. No. 1,062,771 disclosed paving blocks consisting of comminuted natural or artificial stony material, preferably from basalt, granite, porphyry, lava, syenite, quartz, glass, slag, etc., in admixture with clay. Alfred Plant in U.S. Pat. No. 728,290 discloses a floor tile comprised of feldspar, cornwall stone, baryta, glass, fret, quartz, and clay. To impart a marble color, the die is sprinkled with layers of white and bluish dust of metal oxide prior to adding the clay mix, compressing, and firing.

Clay formulations suitable for sewer pipe were disclosed by Carter et al. in U.S. Pat. No. 2,019,619. Russell Dunmire in U.S. Pat. No. 2,601,105 teaches that color can be added to a clay ceramic by dusting the molded product with a colorant prior to firing. A method for making a synthetic stone that resembles a natural stone is taught by Ralph Atkinson in U.S. Pat. No. 1,949,524. In the method, black specks such as cobalt oxide or ore, are indiscriminately distributed therein. The resulting product resembles hornblende granites. Granite is described as, igneous rock of visible crystalline formation and texture. It is composed of feldspar (usually potash feldspar and oligoclase) and quartz, with a small amount of mica (biotite or muscovite) and minor accessory minerals, such as zircon, apatite, magnetite, ilmenite, and sphene. Granite is usually whitish or gray with a speckled appearance caused by the darker crystals, albeit it is also available in various other grades, including earth tone browns, a full range of cool grays to warm grays, various pinks, red, black, green, blue and admixtures thereof. It is an important building stone that is load bearing and being resistant to weathering.

Typical kiln fired bricks utilized in masonry construction are made of clay or shale. The bricks are typically molded, dried and burned in kilns. There are several methods of molding bricks and other building blocks. There are several qualities of bricks and other building blocks, quality being determined by strength, durability, etc. One of the major problems associated with masonry construction is the nonuniformity of building block dimensions due to shrinkage, warping, twisting, etc. Because of these characteristics, mortar is necessary, not only to bond the bricks or other building blocks together, but also to smooth out the irregularities thereof.

M. A. Lefevre teaches an apparatus for grinding bricks or the like in U.S. Pat. No. 3,292,310. The apparatus grinds all six sides of a brick, wherein in successive passes a pair of opposing sides are ground forming right angle edges. After three passes all the opposing sides of the finished brick are in parallel planes. The finished brick is substantially a rectangular parallelepiped.

Bricks ground using Lefevre's apparatus are suitable for bonding using more modern adhesives, instead of mortar, as there is no need to accommodate distortions. Another advantage of not using mortar is that, in many respects, mortar is the weak link in masonry construction. It normally has less compressive and tensile strength than the building blocks it joins. The shear strength of masonry is a function of the bond strength of mortar to the associated brick or other building block, and frictional resistance at the building block-mortar interface. The water tightness of masonry construction is primarily dictated by the characteristics of the mortar, which is more water permeable than brick and most other building block materials. While so much depends on the quality of mortar used, mortars are typically mixed at the job site and can easily be incorrectly mixed or used beyond its useful mix life. Thus, even though masonry construction has been utilized for centuries, there are still some inherent problems pertaining to the lack of uniformity of quality and dimensions in the brick or other building blocks, and to the weaknesses associated with the mortars used therewith.

What is desired is a ceramic synthetic stone product that has the desired building characteristics of brick based materials, the appearance of granite, and the tight tolerances that would enable the use of bonding substrates other than mortar.

SUMMARY OF THE INVENTION

The invention is a ceramic synthetic stone product that has been mechanically ground to a precise shape and dimension, wherein the ceramic synthetic stone product is comprised of a brick material selected, such that when ground, the grinding exposes an interior surface that is similar in appearance to a grade of granite. The interior surface is typically a blend of crystalline components and amorphous components. The interior surface can be whitish or gray with a speckled appearance caused by the darker crystals, earthtone browns, a full range of cool grays to warm grays, various pinks, red, black, green, blue and admixtures thereof. The ceramic synthetic stone product is load bearing and resistant to weathering.

The shape of the ceramic synthetic stone product is typically that of a vitrified brick, a tile, an architectural stone, a curvilinear block, a trapezoidal block, or a decorative plate. The ceramic synthetic stone product is comprised of a brick composition that typically is based on shale and clay, clay being substantially Al₂0₃.2Si0₂.2H₂0. The clay can additionally contain spodumene and petalite. Spodumene is largely Li₂0.Al₂0₃.Si0₂. Other well documented brick material additives include silica; oxide pigments such as cobaltic oxide, cobaltous oxide, iron oxide, titanium oxide, nickel oxide, chromium oxide, antimony oxide, magnesium oxide, alkali oxides, and zinc oxide; other metal oxides, such as calcium oxide, yttrium oxide, molybdenum oxide; and various polymeric (i.e., cellulosic polymers, polyethylene, polyvinyl alcohol) and cement (i.e., calcium aluminates) binders. The brick material can be further comprised of feldspar, kaolin, and various granite materials, including granite dust and ground granite. The reader is reminded that feldspar is any of a group of hard crystalline minerals that consist of aluminum silicates of potassium or sodium or calcium or barium, and is the major precursor to clay and kaolin.

The brick materials are wetted, mixed, extruded, molded, dried and vitrified in a kiln. Nominally, the firing temperature is from about 1100 to about 1650° C. Organic binders are burned off, and the hydrates are substantially dehydrated, forming glass materials.

The surface texture of brick affects its overall appearance, but whether the texture is die skin smooth, wirecut or matt semi-smooth, or thorn face rough, an exterior surface of the molded brick material tends to be disproportionately composed of the more plastic components (e.g., alumina) of the composition.

As discussed in the Background, during the firing in the kiln the dimensions of bricks change due to shrinkage, warping, twisting, loss of water, and uneven heating. The typical size for standard U.S. bricks is 2¼ inches by 3¾ inches by 8 inches with 3 or 10 core holes. Modular U.S. bricks are 2¼ inches by 3⅝ inches by 7⅝ inches; English bricks are 3 inches by 4½ inches by 9 inches; Roman bricks are 1½ inches by 4 inches by 12 inches; and Norman bricks are 2¾ inches by 4 inches by 12 inches. As a rule-of-thumb, the larger the brick, the more apparent is the distortion. Because of the distortion, mortar is necessary not only to bond the bricks or other building blocks together, but also to smooth out the irregularities thereof. Ceramic tiles, architectural stones, curvilinear blocks, trapezoidal blocks, and decorative plates (i.e., trivets), likewise are available in a variety of size and shapes. The more common tile sizes are from 4¼ inches by 4¼ inches up to 12 by 18 inches, and these tiles can be similarly distorted. It is recognized that in addition to rectangles, tiles are also available in many other shapes, such as polygons, and most commonly hexagons. Tiles are individually mounted using a grout type mortar to smooth out the irregularities thereof.

In the instant invention, it is anticipated that bricks and ceramic tiles will be the more common application of the ceramic synthetic stone product. The ceramic synthetic stone product is purposely formed over-sized to allow for a thickness equal to or greater than a thickness of the die skin on at least one side to be ground away, therein exposing the underlying interior surface(s). The exposed interior surface has the appearance of granite when similarly ground. The grinding can initially be coarse, followed by a fine grind that in essence polishes the exposed interior surface of the ceramic synthetic stone product. With products like brick and tiles, it is typically preferable to grind a face side, and two or more perimeter sides.

Furthermore, the starting product can be sufficiently over-sized to allow any distortion to be ground away, as well as the die skin. After grinding, the finished product is uniform and free of distortion that was in the over-sized precursor product exiting the kiln. Similarly, if a purpose of the grinding is also to expose an interior surface, then the product coming out of the kiln must be sufficiently over-size that the grinding does not reduce the dimensions of the finished product to less than the desired size.

As noted in the Background of the Invention, Martial Lefevre, in U.S. Pat. No. 3,292,310, has invented an apparatus for reducingly grinding the six sides of a brick using an apparatus that in successive passes grinds a pair of opposing sides, forming a finished brick, wherein after three passes all the opposing sides are parallel. It is anticipated that conceptually Martial Lefevre's apparatus could potentially be adjusted to grind away the die skin on at least one side of the ceramic synthetic stone product, and in applications where it is desired that all the opposing sides be parallel, the Lefevre apparatus could be employed to grind out distortion and grind away the die skin on all the sides. In applications, such as tiles, where the edges are typically beveled, the Lefevre apparatus is not suitable. In general, the Lefevre apparatus is limited to forming square edges, and in ceramic synthetic stone products, where it is desired that the die skin be ground away, but that the opposing sides are not parallel, then the Lefevre apparatus would not be suitable.

A first example of such a non-square edge product is a trapezoidal shaped brick (i.e., voussoir, keystone or springer), which is used in an arch and in other structures having a curvilinear shape, where there are at least two sides that are not in parallel planes. In the instant invention, the ceramic synthetic stone product is ground, therein exposing the interior surface that is similar in appearance to a grade of granite. The brick is mechanically ground to a precise shape and dimension, so that the interior surface is exposed, and, when installed, the trapezoidal side of one brick is flush with the trapezoidal side of an adjacent brick.

Other examples of non-square edged products are bullnosed shaped bricks, sills, and thresholds.

OBJECTS OF THE INVENTION

A principal object of the invention is to provide a brick based synthetic stone product that has a ground and/or polished surface that is similar to grades of granite.

Another object is to provide an engineered material product that is a building material that has weather resistance comparable to brick or tile, and superior to cement-based materials.

A further object of the invention is to provide a ceramic synthetic stone product that is ground to a precise shape and dimensions.

An additional object of the invention is to provide a product that is less expensive to manufacture than comparably sized granite building materials.

Another object is to provide a vitreous material having a ceramic glaze.

Another object of the invention is to provide a product that need not be adhered using mortar or grout, where the quantity of the mortar is in part to accommodate for the distortion intrinsic with most kiln-fired brick based products, and can instead be adhered with unconventional, stronger bonding agents like epoxy adhesive systems.

Another object of the invention is to provide the appearance of a ceramic synthetic stone product, which can be selected through formulation of the brick material comprising the product.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects will become readily apparent by referring to the following detailed description and the appended drawings in which:

FIG. 1 is a perspective view of the ceramic synthetic stone product of the invention, that is, a brick that has been mechanically ground to a precise shape and dimension, wherein the ceramic synthetic stone product is comprised of a brick material selected, so that when ground, the grinding exposes an interior surface that is similar in appearance to a grade of granite.

FIG. 2 is a perspective view of an over-sized precursor brick to the finished brick shown in FIG. 1.

FIG. 3 is a perspective bottom view of a ceramic tile, wherein the die skin of the face and the sides of the tile have been ground away, therein exposing the interior surface. The bottom of the tile has not been ground, and the die skin is still present.

FIG. 4 is a perspective top view of the ceramic tile shown in FIG. 3.

FIG. 5 is a planar top view of an embodiment of the ceramic synthetic stone product, wherein the product is a ceramic synthetic granite hexagonal tile with a ceramic glaze.

FIG. 6 is a planar top view of the ceramic synthetic granite hexagonal tile shown in FIG. 5 prior to being processed. The perimeter region between the dashed line and the solid line is to be ground away and beveled. The die skin on the face of the hexagonal tile is to be ground off and a ceramic glaze added and vitrified in a second firing, producing a high gloss synthetic granite tile.

FIG. 7 is a perspective top view of a trapezoidal block, wherein two opposing pairs of the six sides are substantially parallel, and will be visible when assembled, and two of the sides are trapezoidal and still have the die skin.

FIG. 8 is a perspective bottom view of the trapezoidal block shown in FIG. 7 showing that the opposing sides are similar in appearance.

FIG. 9 is a planar frontal view of an assemblage of trapezoidal blocks formed into an arch.

FIG. 10 is a cut-away sectional view of a ceramic synthetic stone product comprised of a brick material that has a die skin, wherein the composition of the material is similar in appearance to a grade of granite.

DETAILED DESCRIPTION

The invention is a ceramic synthetic stone product comprised of a brick material, which can additionally have silica; oxide pigments; binders; and granite derived materials, including granite dust and ground granite. The composition of the synthetic stone product is selected to form a vitrified product that is similar in appearance to a desired grade of granite. The average chemical composition of granite by weight % is SiO₂—70.18, TiO₂—0.39, Al₂O₃—14.47, Fe₂O₃—1.57, FeO—1.78, MnO—0.12, MgO—0.88, CaO—1.99, Na₂O—3.48, K₂O—4.11, H₂O—0.87, and P₂O₅—0.19. However, granite is very diverse in color, homogeneity, cyrstallinity, size of crystallites, and patterns. The composition of the instant invention is not limited to the composition of granite, but instead generally falls into the range of being substantially a brick material with additives that influence the appearance so as to achieve an appearance similar to a desired grade of granite.

During molding and firing, the ceramic synthetic stone product forms an outside layer that is disproportionately high in composition of the more plastic components of the brick material and, in particular, alumina. The outside layer is conventionally known as the die skin. The die skin must be ground off to expose the underlying interior surface that is similar in appearance to a grade of granite. The grinding process can accomplish any or all of the following: bevel edges; remove distortion; level, curve or groove surfaces; and polish the exposed interior surface.

In the present invention, the interior surface can, in addition to being ground and polished to a smooth finish, be coated with a ceramic glaze to further enhance gloss.

Referring to FIG. 1, the ceramic synthetic stone product 10 illustrated is a brick 50 generally in the form of a rectangular parallelepiped that, instead of looking like a conventional brick that is usually a slightly mottled dull reddish brown, looks like a rectangular block of granite. Granite is often gray with a speckled appearance caused by darker crystals, as is depicted in FIG. 1. Clay and shale materials have been preferably selected which are low in iron, so as to tone down the nominal reddish brown appearance. The die skin of the brick 50 has been ground away, exposing the interior surface 14. The grinding exposes the crystalline components, which are indigenous to granite, but are nominally covered by the plastic amorphous components of the brick material, and the grinding provides access to the interior of the synthetic stone. These crystalline components are not unlike the crystalline components of granite, which are similarly exposed during the processing of granite. The grinding also removes distortions of the brick formed during its manufacture, and in particularly during the de-molding and firing process. The dimensions of bricks change due to shrinkage, warping, twisting, loss of water, and uneven heating, and the grinding is used to eliminate or ameliorate the distortions. To accommodate for the loss due to grinding, the unfinished brick 40, as shown in FIG. 2, is proportionately oversized. The thickness of the die skin is nominally on the order of 2 mm or less, so the amount of distortion is generally determinative as to how much grinding will be required, as the distortion can be several orders of magnitude greater. As a guide, the distortion is generally less than 5 mm per side for a standard US brick. A cut-away partial sectional view of an unfinished ceramic brick 40 is shown in FIG. 10. As can readily be seen, the die skin 12 of the unfinished brick 40 covers the interior surface 14, which has a granite appearance.

Referring to FIG. 3, the ceramic synthetic stone product 10 is embodied as a ceramic tile 60. In the illustrated embodiment the ceramic tile 60 has a bottom 62 with a die skin 12, a synthetic granite face 68, beveled edges 64, rounded corners 70, and synthetic granite sides 66. The die skin 12 has been removed from all sides except the bottom 62, therein exposing the interior surface of synthetic granite. FIG. 4 is a top view of ceramic tile 60.

Another variation of the ceramic synthetic stone product 10 is illustrated in FIG. 5, which is a polygonal stone 80. The polygonal stone is hexagonal plus a face and bottom. The polygonal stone has a clear ceramic glaze that adds to the gloss and seals the stone. The polygonal stone 80 is formed by grinding down the over-sized unfinished stone 42 shown in FIG. 6. The edges 84 of the sides 82 of the over-sized unfinished stone 42 have been trued by mechanical grinding, thereby removing all distortion, and simultaneously grinding away the die skin 14. The face 86 is ground and polished, and then coated with a ceramic glazing and fired.

Another variation of the ceramic synthetic stone product 10 is illustrated in FIG. 7 and FIG. 8, which is a trapezoidal block 90. Examples of applications for the trapezoidal block 90 are circular or curvilinear patios, and arches. An arch 98 made with the invented blocks is illustrated in FIG. 9. As can readily be seen by inspection, the trapezoidal block 90 has some sides that still have a die skin, and other surfaces where the underlying synthetic granite is exposed. In the illustrated trapezoidal block 90, it is anticipated that mortar will be employed to adhere the trapezoidal blocks, and therefore only the sides that will be visible are ground exposing the synthetic granite interior surface 14. The trapezoidal block first side 92 shown in FIG. 7, and opposing trapezoidal second side 94 shown in FIG. 8 are not ground. If the trapezoidal block is to be adhered using an adhesive that is less forgiving of distortion, for instance an epoxy or acrylic adhesive, then the trapezoidal sides are preferably ground to eliminate distortion and improve contact.

SUMMARY OF THE ACHIEVEMENTS OF THE OBJECTS OF INVENTION

From the foregoing it is readily apparent that we have invented a ceramic synthetic stone product that provides a brick material that has a ground and/or polished surface that is similar to grades of granite. The invention is an engineered material that has weather resistance comparable to brick or tile, and superior to cement-based materials. The ceramic synthetic stone product that can be ground to precise shape and dimensions has the following attributes: it is less expensive to manufacture than comparably sized granite building materials; it can be adhered using stronger bonding agents like acrylic and epoxy adhesive systems; and the appearance of the ceramic synthetic stone product can be selected through formulation of the brick material.

It is to be understood that the foregoing description and specific embodiments are merely illustrative of the best mode of the invention and the principles thereof, and that various modifications and additions may be made to the invention by those skilled in the art, without departing from the spirit and scope of this invention, which is therefore understood to be limited only by the scope of the appended claims. 

1. A ceramic synthetic stone product that is comprised of a brick material selected, so that when ground, the grinding exposes an interior surface of the brick material that is similar in appearance to a grade of granite.
 2. The product, as claimed in claim 1, wherein said interior surface is covered by a die skin.
 3. The product, as claimed in claim 2, wherein said die skin is disproportionately rich in a plastic amorphous component of said brick material.
 4. The product, as claimed in claim 2, wherein said interior surface is a composite of crystalline components and amorphous components, where the crystalline components are not masked by the amorphous components.
 5. The product, as claimed in claim 2, wherein said product is a vitrified brick, a tile, an architectural stone, a curvilinear block, a trapezoidal block, or a decorative plate.
 6. A ceramic synthetic stone product that is comprised of a brick material covered by a die skin, wherein said product is formed by reducingly grinding off at least one side of the die skin, thereby exposing an interior surface.
 7. A ceramic synthetic stone product, wherein said product is formed by precisely, reducingly grinding out distortions of an over-sized precursor product covered by a die skin, and reducingly grinding off at least one side of the die skin of the over-sized precursor product, thereby exposing an interior surface.
 8. The ceramic synthetic stone product, as claimed in claim 7, wherein said product is a vitrified brick, a tile, an architectural stone, a curvilinear block, a trapezoidal block, or a decorative plate.
 9. The ceramic synthetic stone product, as claimed in claim 7, wherein said interior surface is similar in appearance to granite.
 10. The ceramic synthetic stone product, as claimed in claim 9, wherein the die skin is ground off all but one side of said product.
 11. The ceramic synthetic stone product, as claimed in claim 10, wherein the interior surface is fine ground to a polished finish.
 12. The ceramic synthetic stone product, as claimed in claim 10, wherein the interior surface is coated with a ceramic glaze.
 13. The ceramic synthetic stone product, as claimed in claim 7, wherein said product is comprised of feldspar.
 14. The ceramic synthetic stone product, as claimed in claim 10, wherein the interior surface is finely ground to a polished surface.
 15. The ceramic synthetic stone product, as claimed in claim 7, wherein said product is comprised of kaolin.
 16. The ceramic synthetic stone product, as claimed in claim 7, wherein said product has beveled edges.
 17. The ceramic synthetic stone product, as claimed in claim 7, wherein said product has rounded corners.
 18. The ceramic synthetic stone product, as claimed in claim 7, wherein said product is comprised of: clay, oxide pigments; and a binder.
 19. The ceramic synthetic stone product according to claim 18, wherein said product is further comprised of: granite materials.
 20. The ceramic synthetic stone product according to claim 19, wherein said product is further comprised of: silica.
 21. The ceramic synthetic stone product, as claimed in claim 7, wherein said product is comprised of: shale; oxide pigments; and a binder.
 22. The ceramic synthetic stone product, as claimed in claim 6, wherein said interior surface has the appearance of a grade of granite.
 23. The ceramic synthetic stone product, as claimed in claim 7, wherein said interior surface has a speckled whitish or gray, or earth tone brown, or pink, or red, or black, or green, or blue, or a blend thereof appearance.
 24. The ceramic synthetic stone product, as claimed in claim 1, wherein said interior surface has an appearance of a speckled whitish or gray, or earth tone brown, or pink, or red, or black, or green, or blue, or a blend thereof.
 25. A method for making a ceramic synthetic stone product, said method comprising: forming an oversized precursor product comprised of a brick based material, wherein said precursor product has at least one side; firing the oversized precursor product forming a ceramic stone material; and grinding at least one side therein exposing the underlying interior surface, whereby said grinding reduces the oversized precursor product to the ceramic synthetic stone product of a desired dimension. 